.ttr>td:nth-child(2n){
    background-color: rgb(65, 139, 208)
}
.ttr>td:nth-child(2n+1){
    background-color: rgb(10, 240, 240)
}
body{
    font-size: 15px;
    background: url(./图片素材/4.jpg) no-repeat;
    background-size: cover;
    background-attachment: fixed;
}
